



Patented May; 18, 1926.

Unit-En STATES essens PATENT orrics.

CLARENCE r; HARRIS, on NEW YORK, N. Y.. AND NATHANIEL M. ELIAS, or NEWBRUNSWICK, NEW JERSEY.

DIAzowIzArIon or ORGANIC comr eiws.

No Drawing".

This invention relates 'to the diazot-izat-ion of organic compounds, inother words to reactions in which an organic compound is subjected tothe action of-nitrous acid.

Diazotization has heretofore generally .la-eu carried out in dilutesolution, by subjecting an alkali metal nitrite to the action. ofhydrochloric aeid, this reaction being carried on in the presence of thesubstance to be diazotizcd.

According to the present invention, it is rendered possible to carry outthe diazotization in very concentrated or almost anhydrous solution, andby the use of sulphuric instead of hydrochloric acid. Under theseconditions the mechanism of the reaction .whiclrtakes 'place is probablyentirely different from that which occurs in the usual diazotizationprocess.

The process of the presentinreution will he most readily understoodfrom. the following specific example. harin reference to thediazetixationof aniline, itbeing understood. however, that the inventionis notlimited to this use, but. is capable of general application, i

"lhe anilineu'hich is to he treated is mixed with sulphuric acid ofapproximately 93% cmiccntration, the quantity of sulphuric acid beingless than the aniount. which is theoreticzilly required to convert allof the aniline into aniline sulphate, the excess of the aniline being;employed to form a reaction mass of such consistency" that itmay heagitated. Other substances may be substituted for the excess aniline asdiluent. To this mixture is added a catalytic Z1ll10llllt. 0fhydrochloric acid or any other acid whose amine salt is soluble in thediluent employed, which in the example is aniline oil. the amount; ofcatalyst; employed being; varied in accordance with the type ofequipment used, the cooling surface available, and other factors of asimilar nature, the general rule being that. the greater the amount: ofcatalyst employed. the more rigorous the reaction ol'itaincd, but. onlya small fraction of the amountneeded to complete the reaction beingnecessary and this remaining unchanged after react-ion is complete.Inactual practice the reaction has frequently been carried out withcatalyst present in an amount of approximately 2% of the total anilineemployed. "If preferred, the sodium Application filed June 17,

for the diazotizcation 1924. Serial No. 720,517.

nitriteand hydrochloric acid may be mixed before added to the reactionmass, and the catalyst so formed may he added to the reaction mass.Solid sodium nitrite of the desired amount is non gradually added, thetemperature being kept in the neighborhood of tlPil'OXlmtllQl)forty-five degrees. The sodium sulphate formed by the reaction'of thesodium nitrite and the sulphuric acid precipitates out of solution to alarge extent, thus keeping the reaction mass almost anhydrous because ofits great atl'inity for water. When all of the sodium nitrite has beenadded, theauilinc equivalent to the nitrite employed will have beenconverted to diazobenacne and the reac-' lion mass array he. treated inany way that;

.may be desired to separate out the diazoben- Hue or :0 form furtherproducts" from it, in accordance ith the usual practice.

The reaction which talzes place during the above described. process hasnot been definitely" determined, but probably involves the intermediatei'orination of nitrosulphonic acid by the reaction of a mixtureof'nit-rogen oxides whose empiric formula is N Q with sulphuric acid. Ihe nitrosulphouic acid r'eacts with water to oral nitrous acid andsulphuric acid. the nitrous acid being the diazotiziu; agent. it thusappears that nitro sulphonie acid can he used in place of sodium nitriteand snlplniric acid.

The above opinion regarding the mechanism of the reaction is based ontwo facts, one. that concentrated sulphuric acid reacts irith a mixtureof nitrogen oxides to form nitrosulphonic acid whose formula is- Ol l'SO and two that the action can be ON carried .out with nitrosulphonicacid instead of sodium nitrite and sulphuric acid.

What we claim is:

l. The method of diazol-izing an organic amino compound which consir'sintreating the compound with sulphuric and alkali metal nitrite.

2. The n'iet-hodof diazotizing an organic ,3. The method of diazotizingan organic annnoleoinponnd which consists in using nitro'sulphonic acidin the presence of the "said compound, and subjecting the compound totheaction of said acid, in the presence of a catalytic. amount of anacid which foi' ms'an amine salt soluble in 'the diluent employed.; '5

4. The method of diazotizing an organic amino compound which consists insubject- ,ing the compound to treatment \\-'ith nitro 'sulphonic acid.-

5. The method of :dinzotizing aniline which consists in treating anilinewith conccntrated sulphuric acid, adding to this mass n catalytic amountof an acid which forms an aniline salt soluble in the diluent employedandthen adding solid alkali metat nitrite.

7; The method of diazotizing an organic nnnno compound, which consistsin treating with concentrated sulphuric. acid an alkali metal nitrite inthe presence of said compound, and adding to the reuctionniass acatalytic amount of acid whose amine salt is soluble in the diluentemployed.-

In testimony whereof we have aflixed oursignatures to thisspecification.

. CLARENCE P. HARE is.

n NATHANIEL M. ELIAS.

